Using LINQ extension method syntax on a MatchCollection

I have the following code:

MatchCollection matches = myRegEx.Matches(content);

bool result = (from Match m in matches
               where m.Groups["name"].Value.Length > 128
开发者_Python百科               select m).Any();

Is there a way to do this using the LINQ extension method syntax?

Something like this:

bool result = matches.Any(x => ... );

using System.Linq;

matches.Cast<Match>().Any(x => x.Groups["name"].Value.Length > 128)

You just need to convert it from an IEnumerable to an IEnumerable<Match> (IEnumerable<T>) to get access to the LINQ extension provided on IEnumerable<T>.

When you specify an explicit range variable type, the compiler inserts a call to Cast<T>. So this:

bool result = (from Match m in matches
               where m.Groups["name"].Value.Length > 128
               select m).Any();

is exactly equivalent to:

bool result = matches.Cast<Match>()
                     .Where(m => m.Groups["name"].Value.Length > 128)
                     .Any();

which can also be written as:

bool result = matches.Cast<Match>()
                     .Any(m => m.Groups["name"].Value.Length > 128);

In this case the Cast call is required because MatchCollection only implements ICollection and IEnumerable, not IEnumerable<T>. Almost all the LINQ to Objects extension methods are targeted at IEnumerable<T>, with the notable exceptions of Cast and OfType, both of which are used to convert a "weakly" typed collection (such as MatchCollection) into a generic IEnumerable<T> - which then allows for further LINQ operations.

Try this:

var matches = myRegEx.Matches(content).Cast<Match>();

For reference, please see Enumerable.Cast:

Converts the elements of an IEnumerable to the specified type.

Basically it's one way of turning an IEnumerable into an IEnumerable<T>.

I think it would be something like this:

bool result = matches.Cast<Match>().Any(m => m.Groups["name"].Value.Length > 128);

You can try something like this:

List<Match> matchList = matches.Cast<Match>().Where(m => m.Groups["name"].Value.Length > 128).ToList();

EDIT:

 public static IEnumerable<T> AsEnumerable<T>(this IEnumerable enumerable)
 {
      foreach(object item in enumerable)
          yield return (T)item;
 }

Then you should be able to call this extension method to turn it into an IEnumerable:

 matches.AsEnumerable<Match>().Any(x => x.Groups["name"].Value.Length > 128);